1. Field of the Invention - The present invention pertains to semiconductor processing systems, and more particularly, pertains to a movable cantilevered purge system including a movable quartz elephant tube with a paddle for use between a wafer load position, a wafer purge position, and a wafer process position for a substrate processing furnace.
2. Description of the Prior Art - Prior art systems have either provided a wafer load position or a wafer process position, but have not provided for an adequate purging position between the other two positions.
U.S. Pat. No. 4,459,104 to Wollmann, entitled "Cantilevered Diffusion Tube Apparatus and Method"; and U.S. Pat. No. 4,526,534 to Wollmann, entitled "Cantilevered Diffusion Tube Apparatus and Method" each have slots in the bottom of the process tubes.
U.S. Pat. No. 4,543,059 to Whang et al., entitled "Slotted Cantilevered Diffusion Tube System and Method and Apparatus for Loading" describes a diffusion tube apparatus. The reference discloses a large quartz tube with a slot in the bottom. There is one glass sleeve inside the process tube. There are no bellows to support a paddle. The glass sleeve is supported on a single runaway and in close proximity to the process tube.
The present invention overcomes the disadvantages of the prior art by providing a movable elephant tube for use in a wafer load purge and wafer process position, and can include a purge injector and a return exhaust tube in the elephant tube. The moveable elephant tube provides for access to wafer loads and purging of the process tube including accelerated cooling cycles. The alternative embodiment provides for low pressure chemical vapor deposition (CVD) processes.